Use -ffunction-sections by default again

Cranelift now uses the same section name for all subsections which
reduces the size overhead of -ffunction-sections.

src/driver/aot.rs

@@ -333,10 +333,9 @@ fn make_module(sess: &Session, name: String) -> UnwindModule<ObjectModule> {
 
     let mut builder =
         ObjectBuilder::new(isa, name + ".o", cranelift_module::default_libcall_names()).unwrap();
-    // Unlike cg_llvm, cg_clif defaults to disabling -Zfunction-sections. For cg_llvm binary size
-    // is important, while cg_clif cares more about compilation times. Enabling -Zfunction-sections
-    // can easily double the amount of time necessary to perform linking.
-    builder.per_function_section(sess.opts.unstable_opts.function_sections.unwrap_or(false));
+    builder.per_function_section(
+        sess.opts.unstable_opts.function_sections.unwrap_or(sess.target.function_sections),
+    );
     UnwindModule::new(ObjectModule::new(builder), true)
 }